Storage and retrieval systems use masts that move horizontally between storage racks, and carriages that move vertically on the masts. The horizontal and vertical movements are coordinated to place carriages opposite storage spaces in the racks to deposit or retrieve loads. In Deep Entry systems created by Woodson Incorporated, wheel driven rack entry vehicles move between aligned carriage and rack rails. Needs exist for providing improved storing and retrieving warehousing systems while, facilitating automation, decreasing handling times and reducing the costs involved.